Haghia Sophia Museum is located in Sultanahmet across from Sultan Ahmed Mosque. Considered one of the finest architectural works in the world, it was originally built as a church. Construction began during the reign of the Byzantine Emperor Constantine 1, but was only completed in AD 360 during the reign of Constantine II.

The first Haghia Sophia was partially burnt during an uprising. It was repaired by Theodosius II and opened to worship in 415, but was burned to the ground during another public uprising in 532.After the revolts, Emperor Justinian determined to build an unparalleled place of worship and entrusted two architect-engineers from Anatolia, Isidoros and Anthemios, with the task. Building materials were brought in from all the Mediterranean countries. In addition, the columns of a number of Pagan temples in Anatolia, including the Temple of Artemis, were dismantled and used in the building. The construction lasted five years, and Haghia Sophia was once again open to worship. The structure standing today is that which was built as a church by Justinian. Haghia Sophia was occasionally damaged, but was repaired and additions were built. Despite the changes, its essence remains untouched.

Haghia Sophia experienced its darkest days during the Latin occupation, it was looted, damaged and a number of its valuable furnishings were removed and taken to the churches of Europe. When the city once again passed into the control of the Byzantines, the church was in terrible condition. Using limited resources, efforts were made to restore it. It was then badly damaged in the earthquake of 1344 in which parts of it, including a section of the dome, collapsed. The increasingly impoverished Byzantines were unable to repair it and it remained closed for a period. Through the levy of special taxes and collection of donations, the church was once again repaired in 1354. Despite these efforts, Haghia Sophia was not to return to its full glory after the Latin occupation until the conquest of Istanbul. Immediately following the conquest of the city, Sultan Mehmed the Conqueror went directly to Haghia Sophia. But it was in ruins. He decided on that day to convert the church to a mosque, and thus a new period began for Haghia Sophia.

From the first day it became a mosque, Haghia Sophia became a place of enormous significance for Muslims living within the borders of the Ottoman Empire, as well as others. For hundreds of years it has symbolized and been a reminder of the conquest of Istanbul.

The Conqueror created various pious foundations with the aim of ensuring revenue and constructed a mihrab (mosque niche), minaret and medrese. Haghia Sophia was shown special attention after the conquest, and the additions built on its grounds turned it into a great ‘kulliye’ or religious complex. One minaret was added by Sultan Beyazit II and a second by Sultan Selim II. Sultan Mahmud I added a reservoir for ablutions, a primary school, a soup kitchen, a library, a chamber for sultans and a mosque niche. The mosaics were completely plastered over, previously, only the faces had been covered. During this period a number of sultans and members of royalty were buried in the complex. They include: Sultan Selim II, Sultan Murad III, Sultan Mehmed III, Sultan Mustafa I and Sultan İbrahim. Haghia Sophia underwent minor repairs during the Republican period, but was left relatively alone during the war years. American scientists obtained permission from the Turkish government to uncover the mosaics in 1932. While these works were underway, Haghia Sophia was changed to a museum in 1934 and opened to the public in 1935. Haghia Sophia presently functions as a museum.

The dome of the Haghia Sophia, believed to represent the infinity of the cosmos, is most impressive. To think that this dome was built in the 530s contributes even more to the importance of the mosque. Despite being damaged, the mosaics found within Haghia Sophia are among the most precious in the world. The additions of the Ottomans, far from spoiling its original beauty, have only reinforced its magnificence. The calligraphies, on plates 7.5 meters in diameter, the stone work, which gives it a lace-like appearance, and the glazed tiles are all priceless. The primary school, tombs, fountains and reservoir which make up the complex are also of major significance from an architectural standpoint.

Nowadays, Hiaghia Sophia has also gained interest from readers of Dan Brown who is the famous author of the worldwide best-seller “The Da Vinci Code”. At his last novel named with “Inferno” begins in Italy’s Florence, then moves on to Sienna and ends in Istanbul, with approximately 100 pages devoted to ancient sites in Sultanahmet including Hagia Sophia, the Basilica Cistern, the Galata Tower and the Spice Bazaar.

Ever since the novel’s release, Istanbul’s appeal and draw to the writer has been mentioned regularly in the world press. “Inferno picks three of the world’s most strategically significant, antiquity-rich cities as its settings, and Langdon makes a splendid tour guide and art critic throughout,” writes The New York Times.